1. Field of the Invention
The present invention relates to an apparatus for dissolving zinc by means of acid-containing liquid electrolytes. The apparatus includes a container for zinc particles to be dissolved, inlet and outlet devices for continuously admitting and discharging fresh or zinc-enriched electrolytes, and collecting and discharging devices for the gases produced during the dissolution of zinc, such as, hydrogen.
2. Description of the Related Art
Apparatus of the above-described type are already known in the art. In these apparatus, zinc particles are introduced into a container filled with an electrolyte which contains sulfuric acid and the zinc particles are dissolved in the electrolyte. During this dissolving process, the free acid of the electrolyte used in the process is gradually used up, so that it is necessary from time to time to refill with fresh electrolyte. This fresh electrolyte is admitted continuously and the same quantity of electrolyte enriched with dissolved zinc is discharged.
The operation of these known apparatus has several advantages. When the zinc is dissolved, large quantities of hydrogen are produced which cause more or less intense turbulence in the dissolving bath. These turbulences have the result that undissolved particles of the zinc are entrained in the electrolytic liquid which is enriched with dissolved zinc and is being discharged. Also, insoluble dirt particles are being entrained which are also included in the liquid being discharged. Consequently, the electrolytic liquids which are enriched with zinc and are used, for example, for coating metal strips, contaminate the coating to be applied.
Therefore, it has already been proposed to introduce the zinc-enriched electrolytic liquids initially into stilling containers which are to cause a dissolution of the not yet completely dissolved zinc particles and a sedimentation of the dirt particles. However, this manner of operation requires relatively long dwell times in the stilling containers and requires a significantly greater quantity of electrolytic liquid for the circulation. In addition, the stilling containers must be taken out of the circulation for the necessary cleaning, so that a continuous operation cannot be ensured.